diff --git a/src/insets/InsetIndex.cpp b/src/insets/InsetIndex.cpp
index a3a52f1f23..70a16f6e3c 100644
--- a/src/insets/InsetIndex.cpp
+++ b/src/insets/InsetIndex.cpp
@@ -174,7 +174,7 @@ int InsetIndex::docbook(odocstream & os, OutputParams const & runparams) const
 }
 
 
-docstring InsetIndex::xhtml(odocstream &, OutputParams const &) const
+docstring InsetIndex::xhtml(XHTMLStream &, OutputParams const &) const
 {
 	return docstring();
 }
diff --git a/src/insets/InsetIndex.h b/src/insets/InsetIndex.h
index 642d3ee0dc..b7427a1ed0 100644
--- a/src/insets/InsetIndex.h
+++ b/src/insets/InsetIndex.h
@@ -60,7 +60,7 @@ private:
 	int docbook(odocstream &, OutputParams const &) const;
 	/// At the moment, this does nothing. See development/HTML.notes
 	/// for some remarks on what could be done.
-	docstring xhtml(odocstream &, OutputParams const &) const;
+	docstring xhtml(XHTMLStream &, OutputParams const &) const;
 	///
 	int latex(odocstream &, OutputParams const &) const;
 	///